164 SUMMARY OF CURRENT RESEARCHES RELATING TO 



integumentary sense-organs, the lateral and oral sensory ridges, and a 

 lateral sensory organ between the openings of ureter and gonoduct. 

 The kidneys, heart, pericardium, and gonads arise from paired primordia, 

 associated with the mesoderm-bands. The gonads appear to arise as 

 paired invaginations from the anterior pericardium. The development 

 of the remarkable relation between the heart and the gut is described. 



Vascular System of Anodonta cellensis.*— G. Schwanecke gives 

 a detailed and effectively illustrated account of the arterial and venous 

 systems. He deals with the heart, the valves, the circulation in the 

 gills, the kidneys, the mantle, the foot, and so on. The main circulation 

 is from heart to body, from body to gills, from gills to heart. A minor 

 stream is from heart to mantle, and back to the heart. Another stream 

 passes from the body through the kidney to the heart, and an accessory 

 stream through the parenchymatous tissue of the branchial septum 

 instead of through the gills themselves. 



Arthropoda. 

 «• Insecta. 



Structure of Ovary in Insects.f — Paul Govaerts distinguishes, like 

 previous investigators, between panoistic ovaries that have no nutritive 

 cells, but only ova and follicular cells, and meroistic ovaries that have 

 nutritive cells either connected with each ovum or located in the 

 terminal chamber of the ovarian tube (and with or without uniting 

 filaments). He is chiefly concerned with the history of the follicle cells 

 and the ovocytes, as seen particularly in Trichiosoma, Carabus, and 

 GicindMa. In Carabus (and probably in Trichiosoma) the nutritive cell 

 and the ovum has a quite similar nucleus and a similar stage of synapsis. 

 Both have a mitochondrial apparatus, but that of the ovum is a regular 

 crescent ; that of the nutritive cells is diffuse. The nucleus of the 

 nutritive cells becomes much larger than the germinal vesicle. Both 

 show an elimination of nucleolar matter into the cytoplasm, but the 

 details differ. The nutritive cell degenerates, the ovocyte proceeds to 

 vitellogenesis. In short, they have much in common, but they have 

 quite distinct histories, and the nutritive cells cannot be called 

 abortive ova. 



Chromatoid Body in Spermatogenesis of Pentatoma.l — Edmund 

 B. Wilson discusses a chromatoid body simulating an accessory chromo- 

 some in Pentatoma (Rkyiodolomia) senilis Sav. It is of large size, 

 invariably present, and almost always single. A study of the entire 

 spermatogenesis shows that it is neither an accessory nor any other kind 

 of chromosome. It is in fact of protoplasmic origin, first appearing 

 early in the growth period outside the nucleus, whence it may be 

 followed uninterruptedly through all the succeeding stages until it is 

 finally cast out of the spermatozoon. Its nature is problematical, but 

 it is important to note its deceptive resemblance to an accessory chromo- 



* Zeitschr. wiss. ZooL, ovii. (1913) pp. 1-77 (39 figs.), 

 t Arch. Biol., xxviii. (1913) pp. 347-445 (3 pis.). 

 I Biol. Bulletin, xxiv. (1913) pp. 392-410 (3 pis.). 



